The present application relates to a brake switch system and assembly configured for use with a vehicle, such as an automobile.
Automobiles and various other vehicles have brake systems that include rear brake lights. When a driver engages a brake pedal, the rear brake lights are activated in order to signal to other motorists that the vehicle is in the process of slowing down, and/or coming to a halt.
FIG. 1 illustrates a schematic block diagram of a conventional brake system 10. The system 10 includes a battery 12 that supplies power to an electro-mechanical switch 14 operatively connected to a brake pedal 16. The switch 14 is also electrically and operatively connected to rear brake lights 18.
In operation, as the brake pedal 16 is depressed, a portion of the brake pedal 16 physically contacts the switch 14. In this manner, the switch 14 closes and current flows to the brake lights 18, thereby illuminating the brake lights 18. Once the physical engagement between the brake pedal 16 and the switch 14 is broken, such as when a driver releases his/her foot from the brake pedal 16, the switch 14 is opened, current no longer flows to the brake lights 18, and the brake lights 18 are no longer illuminated.
Mechanical brake light switches, such as shown in FIG. 1, have been used for many years with mixed levels of reliability and convenience. These switches, which are used by many original equipment manufacturers, exhibit persistent wear issues and noise level concerns. Nevertheless, mechanical brake light switches continue to be used due to their low cost. However, with continued emphasis on improving reliability and comfort (for example, limiting noise), and the advent of electric vehicles, mechanical brake switches are being reevaluated.
FIG. 2a illustrates a schematic block diagram of a known brake system 20. The system 20 includes a battery 22 that provides power to a Hall effect sensor or device 24 that is in close proximity to a brake pedal 26 that is electrically connected to a relay 28, which, in turn, is connected to brake lights 30. The Hall device 24 is positioned proximate a magnet (not shown in FIG. 2). The brake pedal 26 is part of an assembly that includes a ferromagnetic target or plunger, as explained with respect to FIG. 2b. 
FIG. 2b illustrates a simplified view of a driver 31 depressing the brake pedal 26. As shown in FIG. 2b, as the driver 31 presses the brake pedal 26 in the direction of arrow A, the ferromagnetic target in the form of a plunger 33 attached to the brake pedal assembly moves along with the brake pedal 26 in the direction of arrow A, away from the Hall device 24 and magnet.
Referring to FIGS. 2a and 2b, the Hall effect sensor or device 24 includes a transducer that varies its output voltage or current in response to a magnetic field. The Hall device 24 operates as a switch in the presence and absence of a magnetic field. Typically, the Hall device 24 is OFF when there is no magnetic field, and ON in the presence of a magnetic field.
The brake pedal 26 includes a ferromagnetic target or plunger 33, formed of steel (for example), attached to a portion thereto or formed thereon. When the brake pedal 26 is depressed, the ferromagnetic target or plunger 33 of the pedal 26 moves away from the Hall device 24. During this time, the magnetic field emitted from the magnet changes shape. The Hall device 24 detects this change and switches states, thereby closing the relay 28, which, in turn, activates the brake lights 30 (closing a circuit from the battery 22 to the brake lights 30). When the driver removes his/her foot from the brake pedal 26, the magnetic field changes back, the Hall device 28 switches back to its original state, thereby opening the relay 28 and deactivating the brake lights 30. As such, the system 20 provides a single non-contacting switch point that activates and deactivates the brake lights 30 depending on whether the brake pedal 26 is depressed or not.
FIG. 3 illustrates a schematic block diagram of the Hall device 24 in relation to a magnet 32. As shown, the magnet 32 is a U-shaped magnet having lateral posts 34 integrally connected to a cross-beam 36 that separates the posts 34 from one another by an internal gap 38. The Hall device 24 is positioned within the internal gap 38 between the posts 34.
The magnetic field is typically significant enough to exceed an operational threshold and remain in that state until the magnetic field is removed. In general, the magnetic field of the Earth will not activate the Hall device 24, but many common magnets will provide sufficient strength to activate the Hall device 24. The magnet 32 may be a bonded Neodymium-Iron-Boron (Nd—Fe—B) magnet, for example.
The Hall device 24 may be part of an integrated circuit secured to or embedded within the internal gap 38 between the posts 34. As shown in FIG. 3, the Hall device 34 is positioned within the internal gap 38 at an area 40 that experiences zero magnetic field. The Hall device 34 can also have a positive or negative bias in order to facilitate various magnetic switching characteristics.
FIG. 4 illustrates a schematic block diagram of the Hall device 24 in relation to the magnet 32 and the brake pedal 26. As the ferromagnetic plunger 33 of the brake pedal 26 moves away from the Hall device 24, the position of the zero magnetic field area 40 changes so that the Hall device 24 is no longer within the zero magnetic field area 40. As such, the Hall device 24 detects a change in magnetic field, and switches to an ON position. Thus, the relay 28 (shown in FIG. 2a) is closed, and the brake lights 30 (shown in FIG. 2a) are activated.
Various vehicles also include cruise control. A driver typically activates cruise control while driving on a highway, where the driver can operate a vehicle at a consistent rate of speed for an extended period of time. The cruise control feature allows the driver to drive the vehicle without keeping a foot on the accelerator.
In order to deactivate the cruise control, the driver typically taps the brake pedal. In doing so, however, the brake lights are typically activated. However, the vehicle may not, in reality, be slowing down. Thus, the activation of the brake lights may erroneously indicate that the vehicle is slowing, when the driver actually wishes to increase the velocity of the vehicle.
In general, known brake systems include contact-type connector assemblies that typically include a single switching point. As noted above, however, contact-type connector assemblies exhibit persistent wear issues and noise level concerns. Further, the single switching point may cause an erroneous indication of a vehicle slowing down, when an operator is merely deactivating cruise control.